Process of burning cement clinker by flame impingement and apparatus therefor.



PATENTED JULY 31, 1906.

0. ELLIS. PROCESS OF BURNING GBMENT OLINKER BY FLAME IMPINGEMENT ANDAPPARATUS THEREFOR.

APPLIOATIOKIILED DEE-28. 1906.

2 Q9131; aomz -4%% UNI ATE PATENT orrron.

CARLETON ELLIS, OF WHITE PLAINS, NEW YORK.

PROCESS .OF BURNlNG CEMENT CLlNKER BY FLAME IMPINGEMEN T AND APPARATUSTHEREFOR.

Specification of Letters Patent.

Patented July 31, 1906.

Application filed December 28, 1905- Serial No. 293,687.

To all whont it m/rty concern:

Be it known that I, CARLETON ELLIS, a citizen of the United States, anda resident of White Plains, in the county of Westchester and State ofNew York, have invented certain new and useful Processes of BurningCement Clinker by Flame impingement and Apparatus Therefor, of which thefollowing is a specification.

This invention relates to the makin of Portland cement, which. in thebest 'mo ern practice is burned in rotary or barrel kilns by means of ablast-flame of powdered coal projected from one end of the kiln inheating relation to a continuous stream of the material fed along thefloor of the barrel. These instrumentalities I am able to utilize in anew manner with improved results with respect to the consumption of thefuel, quality of the product, and durability of the apparatus.

The powdered-fuel blast has hitherto been used with certainobjectionable limitations, due principally to the extremely hightemperatures attained and the difficulty of reguating the combustion.Thus although this method has the advantage of affording a strong flameat a long distance from the root of combustion it is also attended withthe disadvantage, among others, of overheating, rapid deterioration oflinings, inflexibility, and waste of fuel.

come customary to employ a long axial flame which is preserved fromextensive contact with the material and lining by a stratum or envelopof air, an expedient which has the effect of protecting the lining andmaterial to some extent from the intense heat of the flame, but whichresults in a waste of heat,

which I am able to reduce. The application of the heat in this manner isnecessarily irregular, and the cement material discharges from the kilnas a mixture of burned and overburned clinker, provided the flame issufficiently powerful with respect to the rate of progression of thecement stream to not discharge underburned clinker. In other words, itis not possible by the present method In burning cement in rotary 1kilns with the powdered-coal blast it has be- I and cool enough to beallowed to impinge directly on the lining or the material Without undueinjurious effect upon either. In the combustion of the powdered coalburning axially in the kiln hi h flame temperatures are developed. TheseI have found to approach 3,000 Fahrenheit. A flame of this temperatureimpinging upon the lining of the kiln would rapidly destroy it, for asthe lining softens the forming clinker passing thereover as the kilnrotates must rapidly abrade said lining.

The coal which is used in the jet is finely ground, and ordinarilyninety per cent. Wi 1 pass through a one-hundred-mesh sieve. Withaxially-injected flames in the prior art it has been found that coarseparticles of coal are frequently blown into the kiln for considerabledistances. There is also a tendency for coal particles to fall out ofthe stream in the front part of the kiln on the clinker, discoloring it,and. in some cases burning there with sufficient heat to give anoverheatto this end of the kiln. case where natural draft currents through thekiln are relied upon to afford part of the air necessary for combustionas the incoming heated air passes directly over such coal particles. I

My invention has principally for its object the overcoming of thesedifficulties and the injection of the coal in suchananneras to.

burn it in the region desired.

For the performance of the process herein set forth and claimed I havedevised a certain novel combination of apparatus, which apparatus isalso claimed herein.

This is particularly the I In the accompanying drawings, Figure l of Iwhich represents a sectional View of a ce ment-kiln, 1 is the inclinedrotatablebarrel lined with refractory material rotating on the rollers 2and operated by the gear mechanism 3. of the kiln. 5 is a housing intowhich the upper end of the kiln projects, which housing is provided witha feed-conveyor 6 for the in- 4 is a hood inclosing the lower end IIOtroduction of the raw material and is also provided with the stack 7. Inthe hood 4 is the outlet 8 for the finished clinker. Inthe hood andpreferably well above the center line or axis of-the kiln is situatedthe. opening 9, into which projects the blast-pipe 10, the annular spacesurrounding which is inclosed by the adjustable plate 11, which is socon structed that the blast-pipe 10 may be moved in any direction inorder to shift the direction of the blast, the flame of which shouldimpinge at a point about ten to twelve feet from the clinker-dischargeend of the kiln. 12 is a fuel-hopper containing powdered coal. 13

is a conveyor discharging the coal in a prede termined stream into thehopper and induction-chamber 14. 15 is a conduit or pipe extending fromthe stack 7 to the inductionchamber- 14. Interposed in this-conduit isthe fan-blower 16 or other mechanical draft appliance. On the suctionside of the fan blower is situated the air-inlet 17. Dampers 18 and 19govern the flow of air and stackgases, respectively, and permit ofadmixture of; ninety-two per. cent. of the former with eight per cent.of the latter, which is a mixture well suited for the purposes of myinvention. 20 is a damper placedon the pressure side of the fan.

In Fig. 2, which is a cross-section of kiln near its lower end, thedisposition of cement material on the floor ofthe kiln is shown. Itwillbe seen that the rotation of the kiln causes the material to pile upon the left-hand side, the motion of the kiln in this case being in thedirection of the hands of a clock. In Fig. 2 the preferred location ofthe opening-9 of the blast-pipe 10 is shown. In ordinary practice thefeed-pipe is entered at some point below the center in the lowerleft-hand quadrant of thekiln-section and is directed into thekilnbarrel along its axis in such a manner that no impingement of theflame occurs. My invention involves the elevation of the blast-pi e to amuch higher point in thekiln above the axis and with a downwardinclination such that the flame positively impinges upon thematerial-and with'a force suflicient to enetrate any stratum of airwhich maybe (ff-awn 111- through the open ngs at the hood; It is evidentthat the application of the flame in this manner with a powdered coaland air blast would result in therapid destruction of the kiln-lining,beside overburning the material to a greater of less extent in the,endeavor to secure the complete burning of all the material. By the useof a regulated amount of stack-gases or steam in admixture with theair-blast the flame is sotemered that no destructive action upon theiii-linings is experienced. Although steam" is not a perma nent gas, andalthough-it often exhibits a catalyzing or accelerating efl'ect oncombustion, yet n the present instance it is sometimes possible to usesteam or water-vapor in regupinging temperature.

lated amount for cooling the flame to an im- The temperature of theflame is lowered gases, and while such a flame for clinkering purposeswould not .be practical as an axial flame because of'its lowertemperature, yet as an impingingflame,owing to its proximity to thematerial, it is just as effective as an axial flame of highertemperature heating the material at a distance by radiation only. It isof course not possible to have every portion of the flame impinge uponthe material; but the flame is prevented from taking-anaxial course bythe downward inclination of: the jet and the major portion thereof im:pinges upon the material. By this. pnoeess combustion occurs in andaround the mate by the use of burned rial, and is therefore conductedunder condi tions of highest efiiciency. Elevation of'the jet to a pointabove the center ofthe kiln results in overcoming the difficultiesheretofore experienced with the impingingflamenamely, those due tothefalling of the heavier particles of coal-dust prematurely in theircourse. I g

It should be observed that the stack gas used. as a diluent is notalways of thesame composition, and care should be taken that sufficientcarbon dioxid be used in the-blast to properly protect the lining of thekiln By diluting the air of the jet with the en!- dothern 'cally actingbodies named it is possible to temper the heat of a coal flamesutficiently to permit said flame u on the cement material. The he ataflorde while sufiieiently high toinstitute clinkering of the cementmaterials, is still not great enough to damage ltilnelinings, as wouldbe the case-with a jet of'coal -dust carried by enough pure airto burnit. The impingement is efiected about tenor twellvefeet fromthe end ofthe-kiln orabout Whereclinkering-begins, and by injecting the flame fromabove the axis in the front end of the kiln tosthis point it is foundthat coalrd'ust direct impingement of does. not drop out of'theflame, asit is-apt to.

do with an axial flame unless high jet velncir. ties are-employed, andtime is given the flame to burn sufliciently throughout its mass. topreclude deposition of'injnrious quantities of coal upon the advancingcement material; The clinkering reaction absorbing littleheat, althoughrequiring a high temperaturetolin stitute it, it is foundthat it goes onbehind the flame and 's completedby'the time the 'clinkeroutlet isreached. The current of hot gases sweeping over-thestreamot'cementmaterial approaching thi elinke p gives the necessary conditions forcalcining I2 5 I What I claim is v j 1. The process of burning cementclinker whichconsistsin ling-predeterminedpnon portions of air andurned-ou-t products. at "combustion, in admixing therewith asuitableproportion of powdered fuel-3 in injecting the mixture into arotary cement-kiln above the pinging on an advancing stream of cementmaterial in such kilns at or near the zone where clinkering normallybegins, a flame of burning fuel carried by a jet of commingled air andtempering-gas the proportion of such tempering-gas 1n the et beingregulated to confine the temperature produced within the upper and lowerlimits of safe clinkering.-

3. The process of burning cement in rotary kilns which consists indirectly impinging on an advancing stream of cement material in suchkilns at or near the zone where clinkering'normally begins, a burningjet of mingled airand pbwdered fuel tempered by an admixture of productsof combustion, the relative roportion of such products of combustioneing regulated to'confineythe temperature produced within the upper andlower limits of effective and safe clinkering.

4. The process of burning cement clinker,

which consists in creating a tempered flame I of clinkering temperatureby combustion of powdered coal in an atmosphere diluted with inertgases, the amount of said inert gases being sufficient to restrict thetemperature within the upper and-lower limits of effective and safeclinkering, 1n impinging said flame directly upon a flattened stream ofcementforming material, in agitating said material while under tratment, and-in removing said material upon transformation into clinker.

5. An apparatus for burning cement clinker comprising an inclined rotarykiln having means in its upper end for the introduction ofcement-forming material and a discharge in its lower part for. the exitof the finished clinker; a sealing-hood inclosing the lower end of thekiln and provided with a downwardlydirected blast-pipe at a point abovethe axis of the kiln, and means for introducing. through said blastipe amixture of powdered fuel,

. products 0' combustion and sufficient air for the combusion ofsaidfuel.

apparatus for clinker comprising a long inclined rotary kiln burningcement having means for the introduction of raw material at the upperend and an exit for the finished clinker at the lower end, means at thelower end for introducing a blast of powdered fuel and a suitablesupporter of combustion, means for excluding air elsewhere of powderedfuel, air and diluent gas, all in predetermined proportions and meansfor directin said "blast. downwardly across the axis of t e kiln andinto direct impingement with material traversing the 8. An apparatus forburning cement clinker comprising alon inclined rotary kiln havin meansfor the introduction of raw material at the upper end and an exit forfinished clinker at-the lower end, means" at the lower end'for theintroduction of a blast of powdered fuel, air and stack gas, all inpredetermined roportions, and means-for directing said lyla'stdownwardly across the axis of the kiln and into direct impingement withmaterial traversing the kiln.

9. An apparatus for burning cement clinker comprising a lon inclinedrotary kiln havin -means for the introduction of raw material at theupper end and an exit for finished clinker at the lower end, andflameproducingmeans thereforcomprisin aburner arranged to direct a flameinto irect'impilplgement upon, the material traversing said a feeddevice supplying said burner with powdered fuel, an air-supplying meansfor transporting said fuel to and through the burner and means fordiluting the air sup lied York and State of New York, this 26th day.

of December, A. D. 1905.

CARLETON ELLIS. Witnesses:

FLETCHER P. SCOFIELD,

FRED I. SMITH.

